Field of the Disclosure
The present disclosure relates to a process for extracting and recovering a perfluoropolyether from a lubricating grease.
Description of Related Art
Perfluoropolyether (PFPE) oils are highly valued for properties including high-temperature performance, non-flammability, chemical inertness, superior stability and lubricity. Lubricating grease compounds, which possess similar properties, are created by combining the PFPE oil with a variety of thickeners and optionally other additives to meet the requirements of different applications.
Lubricating greases are manufactured so that the PFPE oil and the thickeners and other additives do not easily separate. This is extremely important in lubrication applications that experience high temperatures or high mechanical loads. An example of this requirement is in the aerospace industry which has adopted a military specification MIL-PRF-27617G that limits the amount of oil separation for various grades of grease. MIL-PRF-27617G Type II grease has a maximum allowance of oil separation of 15.0% when the grease is exposed to a temperature of 204° C. for a total of 30 hours. The oil separation is measured according to ASTM Method D6184 Standard Test Method for Oil Separation from Lubricating Grease.
Manufacturers that produce the lubricating grease compounds and the OEMS that consume the lubricating grease compounds generate waste streams of grease. The grease waste occurs during equipment cleanouts or during product transitions or during incomplete grease product removal from a package or other process steps that are common to manufacturing operations. The PFPE oil in the grease waste stream is not affected by contact with the additives or by the time in the waste stream, and the PFPE oil retains all of its valuable properties.
Therefore, there is a need to develop a cost-effective and environmentally-friendly process that is capable of separating the PFPE oil from the grease and recovering the oil for use.